Spark-plug



E. S. SAVAGE.

SPARK PLUG.

APPLICATION FILED men, 1919- Patented Nov. 23,1920.

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v @TTORNEYS.

PATEN OFFICE.

EDWARD S. SAVAGE, OF ROCHESTER, NEW YORK.

SPARK-PLUG.

Speciiication'of Letters Patent. Pate ted N 23 1920.

Application filed August 25, 1919. Serial No. 319,705.

To all whom it may concern:

Be it known that I, EDWARD S. SAVAGE, a citizen of the United States, and resident of Rochester, in the county of Monroe and State of New York, have invented certain new and useful Improvements in Spark- Plugs, of which the following is a specifi-' cation. I

The present invention relates to spark plugs, and more particularly, to the type in.

which an auxiliary sparking means is provided visible from the exterior of the cylinder, so that the operation of the spark plug may be ascertained without removing the spark plug from the cylinder. An ob ect of this invention is to provide a construction in which the auxiliary sparking means will not act if the spark is not occurring between the electrodes, notwithstanding the fact that a short-circuit is provided between the insulated electrode and the metallic plug or support. Another object of the invention is to provide an auxiliary sparking means which may be shifted on the spark plug in order that it may be visible from any desired direction.

To these and other ends, the invention consists of certain parts and combinations of parts all of which will be hereinafter described, the novel features being pointed out in the appended claims.

auxiliary. sparking means will act at times when a spark between the electrodes is not being produced. As an instance, if a carbon coating covers the exposed surface of the insulator, an electrical circuit will exist through the carbon coating between the electrodes, permittinga current to pass which vwill not-be distinguishable, in the auxiliary sparking means, from a circuit produced from a s ark jumping between the electrodes. n this invention the auxiliary sparking means will only act when a spark jumps between the two electrodes, as the exposed insulating surface between the two tral openin electrodes is greater than the ex osed insulating surface between either 0 the electrodes and the metallic plug or support, and as a consequence a circuit through the carbon on the msulatorbetween one of the electrodes and the metallic support will shortc1rcu1t the auxiliary sparking means.

The invention further provides for the mounting of the auxiliary sparking means so that the auxiliary spark may be shifted in order that it may be viewed from the desired side of the engine.

, Referring to the embodiment of the invention herein shown, 1 indicates the metallic support or plug which has a central opening and a reduced screw-threaded extension 2 adapted to be inserted in the cyl- 1nder. Th1s plug carries two electrodes 3 and 4 insulated from each other and from the metallic support. This insulation is secured in this instance by providing an elongated insulator'5 arranged centrall in the plug with the electrode 3 central y positioned therein. The insulator may be secured in the plug in any suitable manner, but in this instance it has a surrounding annular rib 6 held between an internal shoulder 7 on the plug or support and an internal shoulder 8 formed on a collar 9 which is fitted in the outer enlarged end of the centhrough the metallic plug or support. T e outer end of this insulator 5 carries the binding post 3 electrically connected to the electrode 3, whereas the inner end of the insulator is tapered at 10. The

inner end of the central opening through the plug or support being cylindrically formed, there is thus provided a chamber or pocket 11 between the inner end of the insulator and the metallic plug or support giving a wide surface on the insulator over which the current must travel in order to reach the metallic plug or support from the electrode 3.

The electrode 4 is insulated from the electrode 3 and the metallic plug or support -1 in any suitable manner. In this instance this electrode is eccentrically arranged with reference to the plug, and the insulator, and has its inner end turned laterally at 12, a

throughout its length and being extended onto the laterally turned .portion 12. The

metallic support or plug 1 has at its inner end a hood 14 which partially surrounds the .or support. the insulator become coated with carbon,

projecting end of the terminal 4, and proects beyond the tapered end 10 of the 1nsulator 5 with its base nearer to the center of the spark plug than the longitudinally extending portion of the insulator 13. The purpose of mountin /the electrode 4 in the manner set forth is to provide a eater exposed insulating surface between t e two electrodes 3 and 4: than is provided between the central electrode 3 and the metallic plug By this arrangement, should current will travel from the electrode 3 to the metallic support or plug 1 before it will pass to the electrode 4 by way of the insulating surface, and in this way the electrode 4 will be short-circ'uited.

Arranged between the'electrode 4 and the metallic support or plug 1 is the auxiliary sparking means. This means in this instancecomprises a ring 15 arranged about the insulator 5 at the outer end of the metallic support or plug 1. Associated with this ring electrode 15 is .a projecting electrode 16 which depends from the top wall of a housing 17, said housing being rotatably mounted upon the plug or metallic support 1 preferably through an annular flange 18 at its lower end engaged by a ring 19 secured to the plug above the flange, said ring in addition retaining said rotatable housing '17 to the plug. This housing 17 may have in its side wall a view opening closed by a lens 20, this view opening being directly opposite the depending electrode 16, so that when the housing is turned the electrode 16 and the View opening maintain their relative positions. The purpose of mounting the auxiliary sparking means so that the auxiliary spark may be shifted to any desired point about the spark plug is to permil; bringing of the auxiliary spark into convenient position to be viewed from the desired side of the-engine.

'It will be apparent from the foregoing that as long as a spark is jumping from the electrode 3 to the electrode 4, an auxiliary spark will jump from the ring electrode 15' to the projecting electrode 16, the current then passing through the metallic housing 17 to the metallic support 1. should the exposed insulating surfaces between the electrode 3 and the metallic support 1 become coated with carbon to such an extent that current will pass'from the electrode 3 to the metallicsupport 1, then the auxiliary sparking means will be shortcircuited and, as a consequence, the user of the plug will be advised that the main spark is not occurring. As the distance over the exposed insulating surfaces between the electrode 3 and the metallic plug or support 1- is less than thedistance over the exposed insulating surfaces between the electrode However,

mg means without a spark jumping from the electrode 3 to the electrode 4.

What I claim asm invention and desire tov secure by Letters atent is-: v

1. In a spark plug, a metallic support, an electrode, an electrical connection between said electrode and said support provided with auxiliary sparking means, a second electrode, and insulation between the electrodes, the shortest distance over the exposed surfaces of suchinsulation being greater between said electrodes than between the second named electrode and the metallic support. I

' 2. In a spark plug, a metallic support, an electrode, an electrical connection between said electrode and said support provided with a spark gap visible from the exterior of the plug, a second electrode, and insulation between the electrodes, the shortest distance overthe exposed surface of such insulation between the electrodes being greater than the shortest distance over the exposed surface between the second named electrode and the metallic support.

3. In a spark plug, a metallic support,'two main electrodes, both of which are insulated from each other and from the metallic support, and an electrical connection between one of said main electrodes and the metallic support embodying an auxiliary spark gap formed by two electrodes, one of which has an extended surfaceand is connected directly to one of the main electrodes, and the other of which is in the form of a point and is connected directly to the metallic support, said last named electrode of the auxiliary spark gap being shiftable with reference to the main electrodes and to the electrode having the extending surface so that the position of the spark gap may be shifted.

4. In a spark plug. a metallicsupport, two electrodes, both of which are insulated from each other and from the metallic support,

and an electrical connection between one of the electrodesand the metallic support embodying an auxiliary spark gap formed by two electrodes, one of which directly connects with one of the main electrodes, and the other of which directly connects with the metallic support, one of said electrodes of L the spark gap having an extended surface while the other is in the form of a point and is shiftable relatively to the main electrodes in a complete circle to change the position of the spark gap.

5. In a spark plug, a'metallic support, two

port embodying an auxiliary spark: gap formed by two electrodes, one of which is directly connected to one of the main electrodes, while the other of which is directly connected to the metallic support, one of said electrodes having an extended surface while the other of said electrodes is in the form of a point and is freely movable relatively to the main electrodes 50 that the position of the spark gap may be readily shifted.

6. In a spark plug, a metallic support, two electrodes both of which are insulated from each other and the metallic support, and an electrical connection between one of the electrodes and the metallic support embodying a spark gap shiftable relatively to the metallic support and to the main electrodes. 7. In a sparkplug, a metallic support, two electrodes carried by the support and insulated from each other and from the support, and an electrical connection between one of the electrodes and the sup-' port embodying an auxiliary spark gap, one of the electrodes of which is in the form of a ring normally fixed relatively to the supsecuring said insulating means against movement in said support, and an electrical connection between one of the main electrodes and the metallic support embodying two electrodes forming a spark gap between them, one of said electrodes being directly connected to the metallic support while the other is directly connected to the main electrode, and one of said electrodes forming the auxiliary spark gap having an extended surface, and being normally fixed in relation to the part to which it is directly connected, while the other of' said electrodes is in the form of a point and is shiftable relatively tc the part to which it is directly connected and relatively to the securing means for the insulator.

and an electrode shiftable about the axis of the ring to vary the position of-the auxiliary spark gap. 1

10. In a spark plug, a metallic support having a central opening, an insulator arranged in said opening and projecting from the outer end thereof, two electrodes providing a spark gap between them, one of said electrodes being arranged centrally of said insulator and the other of said electrodes being arranged ecentrically with ref erence to the first named electrode and insulated from said first named electrode and the metallic support, a ring electrode surrounding the projecting end of the insulator andconnected with the second mentioned electrode, and a shiftable electrode for cooperation with said ring electrode connected with the metallic support and mounted to turn about the axis of said ring to provide a shiftable auxiliary spark gap.

11. In a spark plug, a metall1c support, two electrodes providing the maln spark gap, insulating means between the electrodes and between the electrodes and the metallic support, a ring connected wlth one of said electrodes, a housingmclosing said ring and rotatably mounted on the metallic support and having electrical connection therewith, said housing being provided with a view opening, and an electrode 'eccentrlcally carried by said housing to provlde a spark gap between such electrode and the ring. 12. In a spark plug, a metallic support, an electrode, an electrical 'connectlon between the electrode and the metallic support provided with an auxiliary spark gap, a second electrode, and insulating means between the two electrodes and between such electrodes and the support, said insulating means having a portion surrounding the first named.v

electrode at a point inwardly beyond the metallic support and beyond that portion of the insulating means which surrounds the second named electrode.

13'. In a spark plug, a metalhc support having a hood projecting from the lnner en thereof, two electrodes port, one of said electrodes lying partlally within the hood and projecting laterally therefrom toward the other electrode, and

insulating means between the electrodes and between the electrodes and the metalhc'support, said insulating means having a portion.

projecting beyond the hood about the laterally projecting portion of the electrode, and the exposed surface of the insulating means being greater between the electrodes than between the other of said electrodes and the metallic support.

EDWARD s; sAvAGE.

carried by said sup- 

